A Palladium-Catalyzed Synthesis of β-Ionone from 2,2,6-Trimethylcyclohexanone

Breining, Tibor; Schmidt, C.; Polos, K.

doi:10.1080/00397918708063906

Cited by 17 publications

(7 citation statements)

References 4 publications

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“…2), the 13 C label was incorporated at 2-CH 3 of 2,2,6-trimethylcyclohexanone by methylation of 2,6-dimethylcyclohexanone with 13 C-methyl iodide and lithium diisopropylamide. The 13 C-labeled cyclohexanone was converted to cyclohexenyl triflate, which was subjected to the Heck reaction with methyl vinyl ketone to afford [1][2][3][4][5][6][7][8][9][10][11][12][13] ]-β-ionone (14). This was converted to C 14 -aldehyde according to literature procedure (15).…”

Section: Resultsmentioning

confidence: 99%

Carlactone is an endogenous biosynthetic precursor for strigolactones

Seto

Sado

Asami

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

306

255

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Significance Strigolactones (SLs) were initially characterized as root-derived signals for parasitic and symbiotic interactions with root parasitic plants and arbuscular mycorrhizal fungi, respectively. SLs were later shown to act as endogenous hormones that regulate shoot branching. Carlactone (CL) was identified as a product of three SL biosynthetic enzymes in vitro, and therefore a putative biosynthetic precursor for SLs. However, it was neither detected from plant tissues, nor was the conversion of CL to SL demonstrated in vivo. In this paper, we show that 13 C-labeled CL is converted to SLs in vivo, and that endogenous CL is successfully identified from rice and Arabidopsis . These results demonstrate that CL is a true biosynthetic precursor for SLs.

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Section: Resultsmentioning

confidence: 99%

Carlactone is an endogenous biosynthetic precursor for strigolactones

Seto

Sado

Asami

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

306

255

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“…The synthesis of the 13 C‐labeled [10,11,12,13,14,15,16,17,18‐ 13 C 9 ]‐all‐ trans ‐retinal ( 1b ), containing 9 positions of 13 C‐enrichment, began by trimethylation of ethyl 2‐oxocyclohexanecarboxylate ( 5 ) with [ 13 C]‐CH 3 I, to afford the β‐ketoester 6 (Scheme ). From 6 , acid‐catalyzed hydrolysis and decarboxylation afforded a relatively volatile cyclohexanone, which was converted to vinyl triflate 7 prior to a Heck reaction with methylvinyl ketone that delivered triply‐labeled β‐ionone [ 13 C 3 ]‐4 . The first olefination reaction using doubly 13 C‐labeled triethyl phosphonoacetate ( [ 13 C 2 ]‐2 ) yielded the trienoate [ 13 C 5 ]‐8 as an unseparated mixture of E / Z isomers (~9:1 from 1 H NMR) in 78% yield .…”

Section: Resultsmentioning

confidence: 99%

“…By adaption of a procedure by Breining et al, to a solution of LDA (1.90 M, 21.3 mL, 40.5 mmol) in THF (35 mL) under N 2 at −78°C was added 2,2,6‐tri‐(methyl‐ 13 C)cyclohexan‐1‐one (3.62 g, 25.3 mmol) in THF (35 mL) dropwise over 45 minutes. The mixture was stirred at −78°C for 2 hours before dropwise addition of a solution of N ‐phenyl‐bis(trifluoromethanesulfonimide) (9.02 g, 25.3 mmol) in THF (40 mL).…”

Section: Methodsmentioning

confidence: 99%

“…By adaption of a procedure by Breining et al, a solution of vinyl triflate 7 (3.33 g, 12.1 mmol), NEt 3 (6.75 mL, 48.4 mmol), methyl vinyl ketone (1.97 mL, 48.4 mmol), and [Pd(PPh 3 ) 2 Cl 2 ] (425 mg, 0.605 mmol) in DMF (60 mL) under N 2 was heated at 75°C for 18 hours. The reaction was quenched with H 2 O (50 mL) and the aqueous phase extracted with pentane (4 × 50 mL).…”

Section: Methodsmentioning

confidence: 99%

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Synthesis of isotopically labeled all‐trans retinals for DNP‐enhanced solid‐state NMR studies of retinylidene proteins

Leeder

Brown

Becker‐Baldus

et al. 2018

Labelled Comp Radiopharmac

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Three all-trans retinals containing multiple C labels have been synthesized to enable dynamic nuclear polarization enhanced solid-state magic angle spinning NMR studies of novel microbial retinylidene membrane proteins including proteorhodpsin and channelrhodopsin. The synthetic approaches allowed specific introduction of C labels in ring substituents and at different positions in the polyene chain to probe structural features such as ring orientation and interaction of the chromophore with the protein in the ground state and in photointermediates. [10-18- C ]-All-trans-retinal (1b), [12,15- C ]-all-trans-retinal (1c), and [14,15- C ]-all-trans-retinal (1d) were synthesized in in 12, 8, and 7 linear steps from ethyl 2-oxocyclohexanecarboxylate (5) or β-ionone (4), respectively.

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“…HR of a hetaryl triflate [404] b-Ionone Intermol. HR of an alkenyl triflate [405] Irisquinone and maesanin Intermol. HR of an aryl bromide [406a] Lamellarin-G-trimethyl ether…”

Section: Syntheses Of Heterocycles Natural Products and Other Biologmentioning

confidence: 99%

Cross‐Coupling of Organyl Halides with Alkenes: the Heck Reaction

Bräse

Meijere

2004

Metal‐Catalyzed Cross‐Coupling Reactions

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The carbopalladation of an alkene by an organylpalladium halide is the essential step in one of the major contemporary metal-catalyzed C-C-coupling reactions. About 35 years ago, a Japanese and an American group almost simultaneously designed and executed palladium-mediated coupling reactions of aryl and alkenyl halides with alkenes [1]. In subsequent investigations, Richard Heck and his group developed this reaction into a catalytic transformation and started to demonstrate its usefulness as well as its rather broad scope. The real push to utilize this powerful C-C bond-forming process, however, started only around the mid-1980s, and by now an impressive number of publications has established the meanwhile socalled Heck reaction [2] as an indispensable method in organic synthesis [3]. The applications range from the preparation of hydrocarbons, novel polymers and dyes to new advanced enantioselective syntheses of natural products and biologically active non-natural compounds. The more or less simultaneous developments of mechanistically related variants, namely the Suzuki, Stille, Hiyama, Kumada and Negishi coupling reactions (see Chapters 2, 3, 4, 12 and 15 in this book, respectively) of metallated alkenes and arenes with aryl and alkenyl halides or the metal-catalyzed formation and cycloisomerization of enynes have drawn profit from the improvement of and mechanistic insights into the Heck reaction. This, of course, also applies vice versa. Using only a catalytic amount of a palladium(0) complex or a precursor to a palladium species, the Heck reaction can bring about unprecedented structural changes, particularly when conducted intramolecularly. The full potential of this palladium-catalyzed process is still being further explored, as demonstrated by a total of 2400 relevant publications during the past 10 years, and a continuous annual growth in publications of 15 % per year. Therefore, it is appropriate to say that the Heck reaction is one of the true "power tools" in contemporary organic synthesis [4], competing favorably with the Diels-Alder reaction (25 000 references), olefin metathesis (1500 references), Wittig reaction (15 000 references), or Claisen rearrangement (15 000 references). Scheme 5-1 Mechanism of the Heck reaction [7]. Pd(OTfa) 2 , P(2-furyl) 3 , iPr 2 EtN; Pd(OTfa) 2 or Pd(F 6 -acac) 2 ] and fluorinated phosphanes [90] [91]

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A Palladium-Catalyzed Synthesis of β-Ionone from 2,2,6-Trimethylcyclohexanone

Cited by 17 publications

References 4 publications

Carlactone is an endogenous biosynthetic precursor for strigolactones

Carlactone is an endogenous biosynthetic precursor for strigolactones

Synthesis of isotopically labeled all‐trans retinals for DNP‐enhanced solid‐state NMR studies of retinylidene proteins

Cross‐Coupling of Organyl Halides with Alkenes: the Heck Reaction

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